Anthrax is an infectious disease caused by the Gram-positive spore-forming soil bacterium Bacillus anthracis. The endospores are remarkably resistant to physical stress such as extreme temperatures, radiation, harsh chemicals, desiccation and physical damage. These properties allow them to persist in the soil for many years. The spores are highly infectious. If this durable form of the pathogen has been inhaled, it will kill most victims if treatment does not commence within 24-48 h. In Oct. 2001, several anthrax cases resulted in four deaths in the United States after the intentional release of spores through contaminated letters. In addition to the casualties, widespread panic brought the US Postal System to the brink of collapse. These cases demonstrated the danger of B. anthracis as a biowarfare agent to terrorize civilian populations. Intensified scrutiny of the mechanisms underlying the pathogenicity, the detection and treatment of pathogens such as B. anthracis was an immediate result of the attacks.
On the surface of the exosporium glycoprotein BclA of B. anthracis spores, a unique tetrasaccharide of formula 1b (R═H) has been discovered recently (J. M. Daubenspeck, H. Zeng, P. Chen, S. Dong, C. T. Steichen, N. R. Krishna, D. G. Pritchard, C. L. Turnbough, Jr., J. Biol. Chem. 2004, 279, 30945-30953.) The antigen contains an entirely novel monosaccharide at the non-reducing end that was named anthrose. Anthrose is not even found in closely related species. Thus, the tetrasaccharide is a very attractive target for the elucidation of a highly specific immune response in order to detect selectively spores of B. anthracis and to develop a vaccine against this serious threat. The synthesis of the tetrasaccharide has been reported by D. B. Werz, P. H. Seeberger, Angew. Chem. Int. Ed. 2005, 44, 6315-6318.
